# Questions tagged [mathematics]

The abstract study of topics encompassing quantity, structure, space, change, and other properties

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31 views

### Considering distance in network analysis (Gephi)

I have created a set of nodes (archaeological sites) and ties (connected via certain geographical distances), exported from QGIS. I now have an edge list with weights (distances). Gephi, however, sees ...
51 views

### Band ratio with Euler's number in Google Earth Engine

I've band ratio with exponential equation and Euler's number band_ratio = (0,0039e)^(2,4952*(B2/B4)) Can anyone write it in Google Earth Engine format? Or just input the Euler's number?
29 views

### Buffering a point/line/polygon by a mile in React, using Mapbox to display the result

Firstly, I'm using React and Mapbox to produce a view of a map and to store and buffer points, lines, and polygons. I was wondering what way could I buffer said shapes by a mile or another metric unit....
198 views

### Subtracting image value from corresponding month from image collection in Google Earth Engine

I have extracted sea surface temperature(SST) images from Google Earth Engine for a specific time period and region var start = ee.Date(2012-01-01); var end = ee.Date(start).advance(1,'month'); ...
80 views

### An application for measuring river length?

I'm aware of the coastline paradox and its application to rivers in that the measured length of a river depends on the resolution of the measurement. Is there an application that calculates the centre ...
45 views

### Dividing polygon into tiny polygons of particular size

I would like to divide/cut an irregular polygon into tiny polygons of a particular size(1.6m x 1m) in such a way that most of the irregular polygon area has to be utilized (an OPTIMIZATION MODEL) The ...
197 views

### How to determine left and right side of crossing lines? [closed]

Given two lines of which we know the starting XY points and intersecting point, I need to find which line is left and which line is right. The lines are always crossing and can be turned in any ...
78 views

### Determine if a great circle is on the left or right from a point defined by latitude, longitude and bearing

Given A point coordinate on the map specified by latitude and longitude. Shown as "C" on pictures below. Direction where this point is moving, specified by bearing in degrees (0-359), where ...
23 views

### How can you completely cover the surface of a raster with circles where the radius of the circle is the raster value at its centroid?

This is more of an algorithmic/math problem, but I was wondering if someone could point me in the right direction. There's the common problem of covering a surface with circles of equal sizes, but ...
212 views

### Math formula to calculate GPS location for weighted GPS data points

I'm working to improve the location and accuracy of a map / data-point driven application. I have a collection of locations of interest. Each location of interest has a collection of data points that ...
58 views

### Time-Based Multilateration

I'm not entirely certain, but I think this forum is most appropriate for this question. I know the location of three observers. A nearby source, who's location is unknown emits a beam of radiation at ...
91 views

### Finding line equation (on Earth) using two GPS coordinates

Assuming I have two GPS coordinates, how can I find the equation of Earth horizontal line that passes between them? I tried searching for a method of finding a line on a sphere that passes through two ...
121 views

### Converting to geodetic latitude, longitude

I’m writing a program to determine a vector between two points on earth by taking the difference of the ECEF vectors for each point. I’m using this algorithm: https://www.mathworks.com/help/aeroblks/...
256 views

### ECEF coordinates to geodetic coordinates: Where is error in calculation?

I know, there are several questions to this topic, but I am just searching for the error in my own equations. I have no deeper geodetic background, but I am trying to understand these formulas instead ...
310 views

### High resolution x,y dataset for Mollweide projection convert to latitude and longitude coordinates

I have a 2D array that's 144000 x 64000 that has some values that are irrelevant to the question. Let's say the array can be used like an X, Y coordinate system. I somehow need to get the Latitude and ...
119 views

### How to transform camera calibration parameters to other coordinate system?

I have all camera calibration parameters (X0, Y0, focal length, R0, P0, P1, K0, K1, coarse rotation, rotation, translation) and position of the image in WGS84 (XYZ in meters) and other parameters like ...
55 views

### Seeking documentation about non-iterative UTM to Lat-Long projection formulas

In Hager, John W., James F. Behensky, and Brad W. Drew. "The universal grids: Universal transverse mercator (utm) and universal polar stereographic (ups)." DMA technical manual 8358 (1989). I ...
296 views

### Calculating Center (GPS Point) and Radius (km) of n GPS points

I'm new to GPS and position mapping but i have a background in programing and some of the math related to it. I've been tasked with writing a small golang program that takes n GPS points (DMS) and ...
40 views

### Converting latitude/longitude into a slab number (or item number) and vice versa?

Purpose: To compress the data transmission for the longitude and the latitude. Initially these datas are in the form DD.MM.mmmm: degrees, minutes, ten thousandths of a minute. Latitude stands under 28 ...
217 views

### Calculate weighted azimuth/bearing of a line

Given the line LINESTRING(-9.086532643219698 -7.939337106873815,-1.396102955719698 -0.9775148048290135,-0.780868580719698 -0.7138718839794582,-0.077743580719698 -0.6699297767574899,0.581436106780302 ...
926 views

### Understanding cosine-weighting?

I am studying a paper where they use a method to calculate the vertical distribution of water content (ice, water vapor, cloud water) from the amount of ice on the martian surface. In the paper they ...
38 views

### How is the Point on surface tool calculated in QGIS [duplicate]

I am interested to know how the Point on surface tool works in QGIS 3. I am choosing to use this rather than the Centroids tool which works of the "center of mass" methodology because this creates a ...
147 views

### Applying a two step floating catchment with boundary limitations

The literature states that gravity models and the two step floating catchment area (which in itself is a version of the gravity model) method for analysing the accessibility of healthcare services by ...
125 views

### How to run a Epanechnikov (parabolic) decay in QGIS 3.6 field calculator

Does anyone know how you would implement a Epanechnikov (parabolic) decay to a field in QGIS field calculator. I am trying to apply varying distance decay functions in order to assess the best ...
273 views

### calculating HRMS using NMEA sentences including GPGGA , GPGSV, GLGSV, QZGSV,QZGSA, GPGSA?

I have NMEA sentences including GPGGA , GPGSV, GLGSV, QZGSV,QZGSA, GPGSA and GNGSA. my goal is to achieve HRMS accuracy meter. produced android devices for special intent gives GP/GN GST nmea message ...
419 views

### Procedure of transforming coordinates?

I'm trying to understand the math behind this transformation. I should note that I've been able to perform the transformation using GeoPandas, but I'd like to understand what is going on under the ...
58 views

### How to compare centrality of points in different shaped and sized polygons

Suppose I have several polygons of varying shape and size, each containing a single point. I want to compare the centrality of each point, and determine which point is more central to its polygon. I'm ...
3k views

### Calculate angle between nodes or point in line in QGIS

I want to check the digitization of line in correct direction, so for that I need to know the angle of each node in line. Is that possible in QGIS?
12k views

### How to add meters to EPSG:4326 coordinates? [duplicate]

I've some lat/long in EPSG:4326 coordinate system like Eiffel Tower position : ["lat" : 48.858274,"lon" : 2.2944] For automated tests I would like to get, for every points of my dataset, the x and y ...
213 views

### GRASS GIS: Getting know about stream power index (SPI) computation by r.watershed function

I need to know exact way how stream power index (SPI) is computed by module r.watershed. On the help page is that SPI is α * tan(β), where: α is cumulative upslope area draining through a point per ...
118 views

### Postgresql - problem updating row with complex calculation

A calculation for the replacement value of a tree exists: Variables: index_price for species; circumference of tree; condition measures: vitality, root_injuries, stem_injuries, crown_injuries (A ...
171 views

### What's the math behind moving from a starting point in the direction of another one?

I am working with decimal-degree coordinates for a software and lack geographic background. I want to convert the coordinates to a grid to calculate distances and then move around using standard ...
92 views

### Kriging: Large standard error very close to known value points

I am attempting to create surfaces of strata via Kriging in Arc GIS from borehole data. In addition to the predicted surface I also want surfaces showing 95% confidence above and below the predicted ...
370 views

### Formula for transforming from EPSG:4326 to EPSG:3003 or EPSG:3004

This system is used in Italy. I came across this: It says that lambda zero is 9° if it's to epsg:3003 otherwise if it's to epsg:3004 it's 15° I came up with this Java code, but the result is wrong: ...
7k views

### Converting from ECEF to geodetic coordinates

I am trying to convert an ECEF coordinate to a geodetic coordinate using this procedure, but I don't fully understand the process. It is prefaced by stating the geodetic parameters {a,b,e,e'} are ...
430 views

### Calculate turn required to follow a line of latitude

Lines of latitude are not geodesic except at the equator. So to follow perfect eastern course in the northern hemisphere in a vehicle a left turn is constantly required. We can express a turn as the ...
599 views

### Calculate lat/long as percentage distance between two points (MSSQL)

I've loaded the US road shapes into MSSQL. I've determined the query to locate the segment of road for a specific address. The segment contains a "linestring" from a series of points. I'm trying to ...
955 views

### Estimating resolution of vector data?

I got an old vector dataset with polygons covering a continent. The data was first published on paper at scale 1:5 000 000 and was later digitalized. I don't have the original data and no information ...
5k views

### Translating latitude and longitude into "polar coordinates" around a point

Times Square in New York City has the coordinates (as per Google Maps): 40.7589, -73.9851 The Barrymore Theater has the coordinates (again, as per Google maps): 40.7601, -73.9862 Given that ...
2k views

### Finding the Point of Intersection Between Two Line Segments and Level of Error

I am working on calculating the intersection of two lines. Each line segment is represented as two geographic coordinate pairs. Additionally, each line segment is less than 1km in distance. My ...
334 views

### Creating local coordinate system from orthorectified image from drone

My plan is to use a drone and pix4d to map an area and produce a top down image. I have some position data that is in its own reference frame / Coordinate system. My question is what suggestions or ...
2k views

### How can I calculate the coordinates of a point on the intersection of two parallel lines with a bisecting line with pyQGIS? [closed]

I am building some sort of homemade pyQGIS-Buffer-tool as the existing flat-end-buffer-tools are not working for me ( see v.distance.buffer does not create proper buffers with flat endcaps) Therefore ...
68 views

### Determine on what side of a line my current position is at, no matter orientation

I know that this question has been up before, but I'll give it a shot since it's not exactly the same question. Imagine a straight line consisting of a start point and an end point. The orientation ...
307 views

### Getting lat/lng of an object X inches from the GPS? [duplicate]

I'm working on a project where I have a GPS and two receivers to create a triangle with a transmitter. The problem I'm trying to figure out right now is how can I get the position of the two receivers?...
36 views

### How to resolve a rectangle with know points? [closed]

How do I find the coordinates(lat, lon) for D and E in the following rectangle? I know: A (lat, lon) B (lat, lon) C (lat, lon) AE, BE, AC
878 views

### Bearing to X,Y, Z

I’m working on a small project where I’m testing the ability of a laser to accurately measure the angle of a wire. My control for the experiment gives me X,Y,Z coordinates for a point on the wire and ...
905 views

### How to generate missing points in GPS trajectories?

I have some GPS trajectories that include gps locations recorded on variable frequencies (every 1 min ,5 min , 20 min,etc.)using a geographic projection WGS84. In my work, i need a fine-grained GPS ...
64 views

### calculate turning acceleration from a compass

I have degree and timestamp and want to calculate the turning acceleration. What to trigger if the compass is turning fast. Is there a mathematic way to get an acceleration parameter?